1. Technical Field
The present invention is a method for treating contaminated soils and a vertical rotating tiller, more particularly a rotatable apparatus for breaking up contaminated soils, introducing treatment reagents, and mixing the reagents and the soils to ensure effective remediation.
2. Background Information
Contaminated soils often require addition of various chemical or biological treatment reagents in order to clean the soil. Treatment may include addition of liquid or powder neutralization chemicals (for example, to neutralize acids or bases); stabilization agents (for example, to solidify soils containing hazardous liquids, so that toxic constituents do not leach from the soil); and biological agents (for example, bacteria that consume certain contaminants and render them harmless). Generally, treatment may take place off-site, when contaminated soils are removed to a treatment facility, or treated in place, when the soils are allowed to remain and are treated where they are. Contaminated soils vary widely in composition, even within a single location, both vertically and horizontally, and contaminants are often not dispersed evenly throughout the soils. Further complicating treatment is the common presence in soil of naturally occurring metals, such as iron or lead, in certain locations. Soil make-up varies widely from place to place, and the types and levels of contamination vary as widely. Federal and state imposed standards vary according to the type of contaminant (e.g. heavy metals) and the location. In order for treatment reagents to have the desired effect, they must be thoroughly and evenly dispersed and mixed with the soils and with the contaminants. Therefore, it is necessary to use an effective means of introducing the reagents into the soil, breaking up and mixing the soils, and mixing the reagents with the soils. If the reagents are not well-mixed with the soil, contamination will remain and further treatment will be necessary to meet standards. To facilitate treatment in place, or in situ, an effective mixing apparatus should be mobile and reusable, and require a minimum of set-up on site. Cleaning up contaminated soils can be tremendously expensive, and part or all of the bill is often footed by the taxpayer. A quick and effective piece of treatment equipment can bring great savings in labor and cost.
The present invention is an apparatus and method for breaking up and mixing heterogeneous soils, and blending treatment reagents or other materials with the soils. The apparatus comprises, generally:
(a) a vertically oriented rotatable drive shaft, connected to and driven by a motor external to the apparatus;
(b) a drive assembly connected to the drive shaft;
(c) at least two vertically oriented, rotatable cutting shafts connected to the drive shaft through the drive assembly and at least one support plate, at least one of the cutting shafts being generally parallel to the drive shaft;
(d) a sprocket assembly within the drive assembly connected to the drive shaft, the sprocket assembly comprising at least one rotatable sprocket for each cutting shaft;
(e) a means of rotating the sprockets in a direction counter to the rotation of the drive shaft, the means of counter-rotating the sprockets being driven by the motor, the sprockets being rotatable in the same direction and at the same speed as one another; and
(f) at least two generally horizontally oriented tine assemblies connected to each of the cutting shafts, the tine assemblies being arranged vertically in tandem along each of the cutting shafts, each tine assembly comprising at least one tine, the tines being rotatable with the corresponding cutting shaft, each tine being attached to each tine assembly, each tine having at least one blade at its end. The method herein comprises stabilizing and treating contaminated soils in place by vertically tilling and mixing the soils and simultaneously injecting treatment reagents.